Returning Values from User-Defined Functions
In the previous example, we output an amended string to the browser within the printBR() function. Sometimes, however, you will want a function to provide you with a value that you can work with yourself. If your function has transformed a string that you have provided, you may wish to get the amended string back so that you can pass it to other functions. A function can return a value using the return statement in conjunction with a value. The return statement stops the execution of the function and sends the value back to the calling code.
Listing 6.4 creates a function that returns the sum of two numbers.
Listing 6.4 A Function That Returns a Value
1: <html>
2: <head>
3: <title>Listing 6.4</title>
4: </head>
5: <body>
6: <?php
7: function addNums( $firstnum, $secondnum ) {
8: $result = $firstnum + $secondnum;
9: return $result;
10: }
11: print addNums(3,5);
12: // will print "8"
13: ?>
14: </body>
15: </html>
Put these lines into a text file called addnums.php, and place this file in your Web server document root. When you access this script through your Web browser, it produces the following:
8
Notice in line 7 that addNums() should be called with two numeric arguments (line 11 shows those to be 3 and 5 in this case). These are stored in the variables $firstnum and $secondnum. Predictably, addNums() adds the numbers contained in these variables together and stores the result in a variable called $result.
The return statement can return a value or nothing at all. How we arrive at a value passed by return can vary. The value can be hard-coded:
return 4;
It can be the result of an expression:
return ( $a/$b );
It can be the value returned by yet another function call:
return ( another_function( $an_argument ) );
